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Functioning and vulnerability of continental slope ecosystems: combining stable isotope and visual survey approaches

Functioning and vulnerability of continental slope ecosystems: combining stable isotope and visual survey approaches
Functioning and vulnerability of continental slope ecosystems: combining stable isotope and visual survey approaches
Continental slopes support highly diverse ecosystems, influenced by strong environmental depth-related gradients, but many fundamental aspects of ecosystem dynamics remain poorly understood. Emerging evidences show that human-driven pressures are a primary reason for rapid and unpredictable changes on deep-sea ecosystems. For this reason, it is important to understand the ecological drivers behind community dynamics to improve our ability for a sustainable use and to mitigate impacts.
In a multidisciplinary context, I aimed to explore aspects of continental slope ecosystem functioning, including trophic ecology, community structure and function, and potential human-induced perturbations. I used stable isotope analysis to investigate ecological drivers explaining demersal fish community structure between 500 and 2000 m water depth on the North East Atlantic (Scottish and Irish) continental slope. I show that community-level predator prey mass ratios are invariant along a strong environmental gradient and between feeding behaviours. Results also suggest that body size is responsible for a large proportion of the isotopic niche areas and revealed the effect of increasing depth in resource partitioning, with an indication of a divergent energy supply pathways. Finally, I assessed the present status of an important deepwater vulnerable marine ecosystem in the Porcupine Seabight (NE Atlantic). The Porcupine Seabight was surveyed extensively between 1977 and 1986 and was revisited in 2011 to compare the spatial coverage and size distributions of hexactinellid sponges (Pheronema carpenteri) as an indicator for trawling impact. I found that deep-sea sponge aggregations (a) are still present in the Porcupine Seabight, and (b) do appear to be vulnerable to / under threat from deep-water trawl fishing.
In conclusion, it is shown that isotope-type metrics may be powerful proxies to understand community structure and a useful tool to improve ecosystem-based models. Results here present are suggestive that changes in benthic nutrient cycling communities can affect secondary production of deepwater fish communities. Given the vulnerability of deepwater fauna, it is imperative to outline priorities for conservation as a response to environmental and human disturbances threating deep-sea biodiversity.
University of Southampton
Vieira, Rui Pedro Silva
ef3c005f-e747-47ef-812f-973a9fc0d0d7
Vieira, Rui Pedro Silva
ef3c005f-e747-47ef-812f-973a9fc0d0d7
Trueman, Clive
d00d3bd6-a47b-4d47-89ae-841c3d506205

Vieira, Rui Pedro Silva (2017) Functioning and vulnerability of continental slope ecosystems: combining stable isotope and visual survey approaches. University of Southampton, Doctoral Thesis, 160pp.

Record type: Thesis (Doctoral)

Abstract

Continental slopes support highly diverse ecosystems, influenced by strong environmental depth-related gradients, but many fundamental aspects of ecosystem dynamics remain poorly understood. Emerging evidences show that human-driven pressures are a primary reason for rapid and unpredictable changes on deep-sea ecosystems. For this reason, it is important to understand the ecological drivers behind community dynamics to improve our ability for a sustainable use and to mitigate impacts.
In a multidisciplinary context, I aimed to explore aspects of continental slope ecosystem functioning, including trophic ecology, community structure and function, and potential human-induced perturbations. I used stable isotope analysis to investigate ecological drivers explaining demersal fish community structure between 500 and 2000 m water depth on the North East Atlantic (Scottish and Irish) continental slope. I show that community-level predator prey mass ratios are invariant along a strong environmental gradient and between feeding behaviours. Results also suggest that body size is responsible for a large proportion of the isotopic niche areas and revealed the effect of increasing depth in resource partitioning, with an indication of a divergent energy supply pathways. Finally, I assessed the present status of an important deepwater vulnerable marine ecosystem in the Porcupine Seabight (NE Atlantic). The Porcupine Seabight was surveyed extensively between 1977 and 1986 and was revisited in 2011 to compare the spatial coverage and size distributions of hexactinellid sponges (Pheronema carpenteri) as an indicator for trawling impact. I found that deep-sea sponge aggregations (a) are still present in the Porcupine Seabight, and (b) do appear to be vulnerable to / under threat from deep-water trawl fishing.
In conclusion, it is shown that isotope-type metrics may be powerful proxies to understand community structure and a useful tool to improve ecosystem-based models. Results here present are suggestive that changes in benthic nutrient cycling communities can affect secondary production of deepwater fish communities. Given the vulnerability of deepwater fauna, it is imperative to outline priorities for conservation as a response to environmental and human disturbances threating deep-sea biodiversity.

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Vieira, Rui_PhD Thesis_2017
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Published date: 15 September 2017

Identifiers

Local EPrints ID: 415531
URI: http://eprints.soton.ac.uk/id/eprint/415531
PURE UUID: 5a11a953-4581-4086-93a0-2ae73c8f51ed
ORCID for Rui Pedro Silva Vieira: ORCID iD orcid.org/0000-0001-8491-2565

Catalogue record

Date deposited: 14 Nov 2017 17:30
Last modified: 12 Dec 2021 07:48

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Contributors

Author: Rui Pedro Silva Vieira ORCID iD
Thesis advisor: Clive Trueman

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